Synthetic testosterone was synthesized in 1935 by the German biochemist Adolf Butenandt and Swiss chemist Leopold Ruzicka who both received a Nobel Prize for their work.

Testosterone is the primary male sex hormone synthesized and secreted by the testes. It stimulates the growth and development of male genital organs and secondary sexual characteristics (maturation of the prostate gland, seminal vesicles, penis and scrotum), male-type hair distribution on the face, pubic, chest), laryngeal development, body muscles and fat distribution. Detains nitrogen, sodium, potassium and phosphorus, increases anabolism and reduces protein catabolism. A premature increase in plasma testosterone concentration in the period before puberty causes closure of the epiphyses and stunting. Stimulates the production of erythropoietin and red blood cells. By the mechanism of negative feedback (feedback) inhibits the secretion of luteinizing and follicle-stimulating hormones of the pituitary gland and inhibits spermatogenesis.

In some cases, testosterone has a positive effect on hypertrophy of the prostate gland: the general condition improves, urination disorders decrease, etc. Testosterone may also have a positive effect in angioedema of angina. The positive effect is associated with improved blood circulation and metabolic processes in the heart muscle; there are also favorable changes in the lipid ratio in the blood, an increase in the lecithin / cholesterol ratio.

Testosterone is highly favored by athletes for its ability to promote strong increases in muscle mass and strength. As a naturally occurring hormone, it remains the most popular anabolic steroid and is typically used as the base of all cycles and stacks.